EVALUATION OF DIFFERENT CARBON PRECURSORS FOR THE LIQUID SILICON INFILTRATION PROCESS

The liquid silicon infiltration process (LSI) is a cost efficient manufacturing route to produce fiber reinforced ceramics. The manufacturing route can be split into three steps. In the first step, a carbon fiber reinforced plastic composite (CFRP) is fabricated from a polymer with high carbon yield (carbon precursor). The CFRP is pyrolyzed in the second step to achieve a porous carbon fiber reinforced carbon (C/C). In the third step, liquid silicon is infiltrated to form a dense C/C-SiC composite. The used carbon precursors play a key role in the development of composites with tailored functional properties. The aim of this work is to evaluate several carbon precursors for the liquid silicon infiltration process. One phenolic resin and two cyanate ester resins are investigated. The microstructure of the composites is characterized after each processing step. The mechanical properties of the C/C-SiC composites are determined by three-point bending test. Differences in crack pattern and pore formation during pyrolysis and in silicon infiltration behavior are described. The suitability of the precursors for the manufacturing route is discussed.